The disclosure relates to strengthened alkali aluminoborosilicate glasses. More particularly, the disclosure relates to a method of strengthening such glasses. Even more particularly, the disclosure relates to strengthening such glasses by ion exchange.
The ion exchange process can be used to strengthen alkali-containing glasses by creating compressive stress layers in the surface region of the glass. In general, lithium-containing aluminosilicate glasses are ion exchanged more readily than sodium-containing glasses and greater depths of compression can be obtained in lithium-containing aluminosilicate glasses at lower temperatures and shorter times. However, such lithium-containing aluminosilicate glasses tend to have lower strain and anneal points, and lower temperatures are required for treatment to avoid structural relaxation. In addition, the exchange of sodium for lithium in the glass, results in lower surface compression—which translates into lower surface strength—when compared to the surface compression achieved with the exchange of potassium for sodium in the glass.